The present invention relates to a fuel injection system comprising a pressure boost pump having a pump body defining a pump cylinder and a pump chamber, and also comprising a fuel inlet conduit and a fuel outlet conduit in flow connection with the pump chamber, the conduits each having a one-way valve, and further a piston structure (which may be a simple piston member or a more complex apparatus) inside the pump cylinder and movable along the longitudinal axis of the piston structure.
In addition, the invention relates to a method of operating a fuel injection system that comprises a pressure boost pump having a pump body defining a pump chamber and a pump cylinder and also comprising a fuel inlet conduit and a fuel outlet conduit in flow connection with the pump chamber, the conduits each having a one-way valve, and further a piston structure arranged inside the pump cylinder, in which method during the intake stroke of the piston structure fuel flows into the pump chamber and during the power stroke of the piston structure fuel flows away from the pump chamber via the one-way valve in elevated pressure and temperature.
Such fuel pressure boost pumps are commonly used in so-called common rail fuel injection systems. A known common rail fuel injection system is disclosed in the applicant's U.S. Pat. No. 6,240,901. In the known system, fuel is fed from the fuel tank to the pressure accumulator by means of a high pressure pump, subsequent to which the fuel is injected into cylinders of the engine by means of injectors.
A problem with a pump like this is that lateral forces acting on the piston structure of the pump cause wear of the piston structure and increase the risk of seizure.
It is an aim of the present invention to provide a fuel injection system minimizing the problems associated with prior art. It is an especial aim of the invention to provide a capability for efficiently detecting pressure boost pump malfunctions in a so-called common rail fuel injection system.